MongoDB Limitations
Shakuntala Gupta Edward, Navin Sabharwal · Apress eBooks · 2015
The files in the data directory are named as .0, .1 and so on. The size of the first file as allocated by the mongod is 64MB; all subsequent file sizes increase by factor of 2, so the second file will 128MB, the third file will be 256MB, and so on until it reaches 2GB, post which all files will be 2GB in size. Though the space is allocated to the data files while creation, there might be files that are 90% empty. This unused allocated space is mostly small for larger databases. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.